The present invention broadly relates to thread winding and, more specifically, pertains to a new and improved method and apparatus for winding threads into cross-wound packages.
Generally speaking, the method of the present invention for forming cross-wound packages comprises the steps of guiding a thread arriving from a stationary thread guide by means of a main traverse mechanism containing a moving traverse means through a complete path of traverse movement and laying the thread onto the cross-wound package.
The apparatus of the present invention for forming a cross-wound package employs a thread traverse means of a main traverse mechanism. The thread traverse means causes a traverse movement of the thread which is to be wound up through a complete path of thread traverse movement. The thread extends in the apparatus from a stationary thread guide to the main traverse mechanism.
German Patent Publication No. 3,436,455 shows a wind-up machine using a thread traverse device for moving the thread and in accordance with which the deceleration or acceleration, or both, of the thread movement is reduced in the end regions of the traverse stroke of the thread. In the mentioned embodiments, this is effected by the provision of an air cushion or a suitable stream of air.
Generally known wind-up devices have the disadvantage that the thread portion running through the traverse device or mechanism is not able to follow exactly the reciprocating traverse element because of the very high speed of reciprocation of such traverse element. As a result of the variations in thread tension which arise, this causes a deterioration in the precision with which the thread can be laid in the package to be wound. As a result, ridges can form on the package, and so-called "overthrown ends" can be formed. Also, the reversal point of the thread on the package is not exact and an optimal crossing angle of the threads in the package is not maintained.
In order to avoid these disadvantages it is known to use a so-called double traverse mechanism, that is to insert a preliminary traverse device upstream of the main traverse mechanism. Such an arrangement is known, for example, from the German Patent Publication No. 2,040,479. Most of the known types of main traverse mechanism employ a grooved roller or drum to produce the traverse movement, that is the lateral reciprocation of the thread. In this arrangement, the thread to be wound up runs in a guide groove which is provided over the complete width of the surface of the roller or at least in its two end zones; the guide groove extends on a helical path over the surface and has reversal locations at the roller or drum ends. When the roller or drum is rotating, the groove causes a continuous reciprocating movement of travel of a thread laid therein. The preliminary traverse device usually comprises a traverse thread guide reciprocated along a straight path, as used also in the present invention.
The use of such a preliminary thread traverse device or mechanism provides the advantage that the continual risk of escape of the thread from guidance at the crossing points of the traverse groove in the grooved roller or drum of the main traverse device can be practically completely eliminated. Furthermore, the preliminary traverse device or mechanism provides the advantage of a more uniform tension of the thread to be wound up than can be obtained where this preliminary thread device is omitted. The preliminary traverse device or mechanism substantially provides the force input which is required by the acceleration and deceleration of the thread and due to friction of the thread over the complete traverse path, primarily in the groove. Thus, this force input no longer has to be provided by the main traverse mechanism and the laying of the thread produced by the main traverse mechanism can be carried out more exactly.
Such preliminary traverse mechanisms or devices have rapidly moving mechanical parts, and therefore have the disadvantage that they are subjected to wear during operation. Also, they exert friction and an abrading effect on the thread. Furthermore, the thread can be caught or can jump out of the groove.
Referring to the wind-up machine disclosed in the initially mentioned German Patent Publication No. 3,436,455, it should be remarked that this differs substantially from a double traverse mechanism since the disclosed apparatus has an effect on the thread only in the end regions of the traverse stroke. Thus, this apparatus makes a negligible contribution to the work required for moving the thread. Accordingly, the wind-up machine of this initially mentioned German Patent Publication does not provide the advantages which arise from a double traverse mechanism.